RHO and retinitis pigmentosa: Moreover, photoreceptors with a gene mutation for rhodopsin differentiated from induced pluripotent stem (iPS) cells derived from an affected patient showed an increase in ER stress and apoptosis, which were attenuated by rapamycin [54], suppressing ER stress [55], suggesting the involvement of ER stress in retinitis pigmentosa-induced photoreceptor death.